package com.neuedu.utils;

import java.sql.*;
import java.util.*;
import java.util.concurrent.Executor;

public class ConnectionPool {
    private static final String URL = "jdbc:mysql://localhost:3306/wuye?characterEncoding=utf8&useSSL=false";
    private static final String USERNAME = "root";
    private static final String PASSWORD = "123456";
    /**
     * 连接池内部封装的集合，存放多个连接
     */
    private static List<Connection> pool= Collections.synchronizedList(new LinkedList<>());

    static{
        try {
            Class.forName("com.mysql.jdbc.Driver");
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
        try {
            for (int i = 0; i < 20; i++) {
                Connection connection = DriverManager.getConnection(URL, USERNAME, PASSWORD);
                ConnectionForPool myConn = new ConnectionForPool(connection);
                pool.add(pool.size(), myConn);
            }
        }catch (Exception e){
            e.printStackTrace();
        }
    }

    public static Connection getConnection(){
        Connection conn=null;
        if(pool.size()>0){
            conn=pool.get(0);
            pool.remove(0);
            return conn;
        }else{
            throw new RuntimeException("数据库连接不够用了，请设置初始化更多的数据库连接");
        }
    }

    /**
     * 归还一个连接
     */
    public static void release(Connection conn){
        pool.add(pool.size(),conn);
    }
    static class ConnectionForPool implements Connection {

        private Connection conn=null;

        public ConnectionForPool(Connection conn){
            this.conn=conn;
        }

        @Override
        public Statement createStatement() throws SQLException {
            return conn.createStatement();
        }

        @Override
        public PreparedStatement prepareStatement(String sql) throws SQLException {
            return conn.prepareStatement(sql);
        }

        @Override
        public CallableStatement prepareCall(String sql) throws SQLException {
            return conn.prepareCall(sql);
        }

        @Override
        public String nativeSQL(String sql) throws SQLException {
            return conn.nativeSQL(sql);
        }

        @Override
        public void setAutoCommit(boolean autoCommit) throws SQLException {
            conn.setAutoCommit(autoCommit);
        }

        @Override
        public boolean getAutoCommit() throws SQLException {
            return conn.getAutoCommit();
        }

        @Override
        public void commit() throws SQLException {
            conn.commit();
        }

        @Override
        public void rollback() throws SQLException {
            conn.rollback();
        }

        @Override
        public void close() throws SQLException {
            //conn.close();
            ConnectionPool.release(this);
        }

        @Override
        public boolean isClosed() throws SQLException {
            return conn.isClosed();
        }

        @Override
        public DatabaseMetaData getMetaData() throws SQLException {
            return conn.getMetaData();
        }

        @Override
        public void setReadOnly(boolean readOnly) throws SQLException {
            conn.setReadOnly(readOnly);
        }

        @Override
        public boolean isReadOnly() throws SQLException {
            return conn.isReadOnly();
        }

        @Override
        public void setCatalog(String catalog) throws SQLException {
            conn.setCatalog(catalog);
        }

        @Override
        public String getCatalog() throws SQLException {
            return conn.getCatalog();
        }

        @Override
        public void setTransactionIsolation(int level) throws SQLException {
            conn.setTransactionIsolation(level);
        }

        @Override
        public int getTransactionIsolation() throws SQLException {
            return conn.getTransactionIsolation();
        }

        @Override
        public SQLWarning getWarnings() throws SQLException {
            return conn.getWarnings();
        }

        @Override
        public void clearWarnings() throws SQLException {
            conn.clearWarnings();
        }

        @Override
        public Statement createStatement(int resultSetType, int resultSetConcurrency) throws SQLException {
            return conn.createStatement(resultSetType,resultSetConcurrency);
        }

        @Override
        public PreparedStatement prepareStatement(String sql, int resultSetType, int resultSetConcurrency) throws SQLException {
            return conn.prepareStatement(sql,resultSetType,resultSetConcurrency);
        }

        @Override
        public CallableStatement prepareCall(String sql, int resultSetType, int resultSetConcurrency) throws SQLException {
            return conn.prepareCall(sql,resultSetType,resultSetConcurrency);
        }

        @Override
        public Map<String, Class<?>> getTypeMap() throws SQLException {
            return conn.getTypeMap();
        }

        @Override
        public void setTypeMap(Map<String, Class<?>> map) throws SQLException {
            conn.setTypeMap(map);
        }

        @Override
        public void setHoldability(int holdability) throws SQLException {
            conn.setHoldability(holdability);
        }

        @Override
        public int getHoldability() throws SQLException {
            return conn.getHoldability();
        }

        @Override
        public Savepoint setSavepoint() throws SQLException {
            return conn.setSavepoint();
        }

        @Override
        public Savepoint setSavepoint(String name) throws SQLException {
            return conn.setSavepoint(name);
        }

        @Override
        public void rollback(Savepoint savepoint) throws SQLException {
            conn.rollback();
        }

        @Override
        public void releaseSavepoint(Savepoint savepoint) throws SQLException {
            conn.releaseSavepoint(savepoint);
        }

        @Override
        public Statement createStatement(int resultSetType, int resultSetConcurrency, int resultSetHoldability) throws SQLException {
            return conn.createStatement(resultSetType,resultSetConcurrency,resultSetHoldability);
        }

        @Override
        public PreparedStatement prepareStatement(String sql, int resultSetType, int resultSetConcurrency, int resultSetHoldability) throws SQLException {
            return conn.prepareStatement(sql,resultSetType,resultSetConcurrency,resultSetHoldability);
        }

        @Override
        public CallableStatement prepareCall(String sql, int resultSetType, int resultSetConcurrency, int resultSetHoldability) throws SQLException {
            return conn.prepareCall( sql,  resultSetType,  resultSetConcurrency,  resultSetHoldability);
        }

        @Override
        public PreparedStatement prepareStatement(String sql, int autoGeneratedKeys) throws SQLException {
            return conn.prepareStatement(sql,autoGeneratedKeys);
        }

        @Override
        public PreparedStatement prepareStatement(String sql, int[] columnIndexes) throws SQLException {
            return conn.prepareStatement(sql,columnIndexes);
        }

        @Override
        public PreparedStatement prepareStatement(String sql, String[] columnNames) throws SQLException {
            return conn.prepareStatement(sql,columnNames);
        }

        @Override
        public Clob createClob() throws SQLException {
            return conn.createClob();
        }

        @Override
        public Blob createBlob() throws SQLException {
            return conn.createBlob();
        }

        @Override
        public NClob createNClob() throws SQLException {
            return conn.createNClob();
        }

        @Override
        public SQLXML createSQLXML() throws SQLException {
            return conn.createSQLXML();
        }

        @Override
        public boolean isValid(int timeout) throws SQLException {
            return conn.isValid(timeout);
        }

        @Override
        public void setClientInfo(String name, String value) throws SQLClientInfoException {
            conn.setClientInfo(name,value);
        }

        @Override
        public void setClientInfo(Properties properties) throws SQLClientInfoException {
            conn.setClientInfo(properties);
        }

        @Override
        public String getClientInfo(String name) throws SQLException {
            return conn.getClientInfo(name);
        }

        @Override
        public Properties getClientInfo() throws SQLException {
            return conn.getClientInfo();
        }

        @Override
        public Array createArrayOf(String typeName, Object[] elements) throws SQLException {
            return conn.createArrayOf(typeName,elements);
        }

        @Override
        public Struct createStruct(String typeName, Object[] attributes) throws SQLException {
            return conn.createStruct(typeName,attributes);
        }

        @Override
        public void setSchema(String schema) throws SQLException {
            conn.setSchema(schema);
        }

        @Override
        public String getSchema() throws SQLException {
            return conn.getSchema();
        }

        @Override
        public void abort(Executor executor) throws SQLException {
            conn.abort(executor);
        }

        @Override
        public void setNetworkTimeout(Executor executor, int milliseconds) throws SQLException {
            conn.setNetworkTimeout(executor,milliseconds);
        }

        @Override
        public int getNetworkTimeout() throws SQLException {
            return conn.getNetworkTimeout();
        }

        @Override
        public <T> T unwrap(Class<T> iface) throws SQLException {
            return conn.unwrap(iface);
        }

        @Override
        public boolean isWrapperFor(Class<?> iface) throws SQLException {
            return conn.isWrapperFor(iface);
        }
    }
}

